Responding to your output and regulating your temperature, this adaptive midlayer is key to your layering system on tough ascents in mixed conditions.Specs Fit: Regular Weight: 12oz/343g (Size M) Centre back length: 29in / 74cm (Size M) Insulation: PrimaLoftA(R) Evolve Active insulation (75gsm) Main fabric: Motiv(TM) Aero single jersey outer fabric with odour control treatment (85gsm)